The present invention relates to a method utilized in a photomechanical scanner, or the like, for scanning and recording an original image, and more particularly to a method for recording a duplicate image having both a picture portion and a line drawing portion by combining a picture signal having continuous variable density tone with a line drawing signal, representing letters or characters having binary tone such as black and white.
In an image scanning recorder, such as a color scanner, there is a demand for recording a reproduced image of a plurality of original pictures on a single photosensitive material exactly in accordance with a desired layout. Although the said demand has become partially practical, when a continuous variable density tone picture and a graph or letter having binary tone are synthesized to duplicate the desired layout, it is necessary for the binary tone graph or letter to be processed by high resolving power. However, there exists a serious problem in that although it is necessary for the line drawing portion, consisting of fine lines or letters, to be recorded by the high resolving power so as to be reproduced as they appear, the application of the same high resolving power to the picture inevitably invites a considerable increase in the time required for processing. Furthermore, another problem exists in that when the picture is processed by high resolving power exceeding the actual requirement therefor, a magnetic disc memory generally used for the process of layout requires a considerable increase in the capacity thereof, thereby increasing the time for processing and correspondingly resulting in an increase in cost.
In order to solve the above-discussed problem, the applicant of the present invention has already disclosed a method in Japan Patent Application No. 57-39877, corresponding to application numbers U.S. Ser. No. 471,869, now U.S. Pat. No. 4,553,172, GB No. 8306373, DE No. P3308468.3 and FR No. 8304155, which, however, particularly in view of the screen system for expressing heading letters or the like by the screen pattern, still has some weak points in that the configuration of dots of a screen portion is slightly different from that of a corresponding picture portion, and that the screen orientation does not always coincide with the picture portion.